Lux I or III at low levels?

Since Lux Is are rated at 350ma, while LuxIIIs are spec'd at 700ma, for something around 400ma, should I go for a R bin Lux I or a S-T bin Lux III?

I would go for the LuxIII because first off it dosent have nearly the same tint issues luxIs have, and second off if in the furture you wanted to drive it harder, you could. If you get a LuxIII pick up a T bin, the few extra dollars are worth it to garentee a 'decent' output.

I think the only possible advantages to using a Lux1 over the Lux III are price and the possibility that the tint binning of the Lux 1 at the lower drive level is more likely to be indicitive of what you will get; the latter is suspect however! /ubbthreads/images/graemlins/grin.gif

I suspect that the Lux III is a more efficient LED at any drive levels but I have neither the data or justification based on differences in design to support this suspicion.

Hi, Garageboy.

The answer will also depend on what Vf of those Lux I and Lux IIIs are. Given the same xxxJ bin, then a Lux I R bin will have more lumens/watt than the Lux III T/S bin. Just off top my head, I would think the TxxJ and RxxJ will give off just about the same level of light around 400ma, given Lux I has higher lumens/watt. But thesurefire had a good point, you could always retrieve the lux III later for another use if you prefer.

Another consideration is the 'tint' shift when a lux is underdriven(here will be the Lux IIIs). For example, even though a lux III TW0J will be a (tiny bit of warm) white, when it is underdriven, it could appear warmer(or more yellowish).

I just did a quicky experiment.

I have two XM3s for Elektrolumens and one is brighter and more blueish than the other.

I have an aluminum dummie I made for a different experiment. Both XMs will light up with 1 aa. The lower output whiter XM didn't tint shift that I could see.

The higher output shifted to a more warm white.

It still paints a spot on white walls in bright stark daylight (makes me think a two-stage switch should be created for the XM!).

I like the tint better, so I think I'll go ahead and run it this way!

I don't think this in any way, shape or form answers your question. BUT! Since I have not see a 1W LUX that was anywhere NEAR as white of tint as the 3W, were I you I'd definately go LUXIII!!!!

Lux3 gets my vote too.
But try for a TXO* bin.
It will usually stay quite white and reasonably bright at lower power levels.
I think I saw some of those FS in the Dealers Corner.

Ok, thanks! I thought about swapping out the LED in various Lux I lights, thats all, like the streamlights. My preferred tint is Y0, though, it's unusual.

I would vote for an R bin Lux1. I suspect the tint issues that the old Lux1 had are in the past, since Lumileds has moved the Lux1 to the same phosphor technology as is used in the Lux3.

The Lux1 will be tint binned at a drive level closer to what you will be using, so you can be more sure of its color.

I've built tons of setups at 400mA and below. I've also built quite a few at 200mA and all were based on Lux IIIs. They were all very nice.

The only guideline that I use when building lights to run Luxeons at sub spec current levels is to use XO bin luxeons. Most aren't too worried about color shift unless it gets too blue, or God forbid, green. I've seen YOs go totally blue and WOs get really warm. With the XO bin, I've never had this trouble.

Of course, what I said above is just in general terms. There will likely be many exceptions to the guideline that I try to follow.

hmm..my WO bin driven at 750 is purpleish, not warm

XO bin is my favorite, either Lux I or III. They tend to stay white in any drive levels.